What you do when something isn’t working, is systematically check the whole system. In some cases this means opening little boxes on the wall where you’ll find cables, pipes and … snakes!
Yikes. This one gave me the creeps. Totally harmless but not what you’d expect to see when looking for faulty wiring. It was ferociously fast moving through the box on the wall without finding a way out, time enough to get a nice picture.